This invention is directed to improved equipment for unloading gasoline from tank trucks and more particularly to improvements preventing fuel spillage and the loss of gaseous vapors to the atmosphere.
A significant factor in the cost of gasoline to the consumer is the distributor's cost of delivering the gasoline to the local gas stations. The gasoline is delivered by large tank trucks which are specially equipped to permit the safe and efficient handling of this highly volatile and dangerous product. To this capital expense is added the high labor cost of the specially trained drivers and maintenance personnel.
The high cost of the truck and its associated equipment is due in part to provisions which must be made for containing and controlling the volatile vapors which are displaced from the underground tanks as they are filled from the delivery trucks. For reasons of safety and ecology the displaced vapors are returned to the truck as the gasoline flows into the tank. Ordinarily separate hoses are provided for the gasoline and returned fumes.
In the interest of the economy of the delivery operation, it is important that the gasoline be unloaded as quickly as possible so as to make the most efficient use of manpower and equipment. For this reason, the hoses and associated fittings are very large and cumbersome and the handling and connecting of these hoses tax the strength and edurance of the delivery man. This is especially true in the case of some of the more recently introduced equipment where the gasoline and vapor return hoses are coupled together in a paralleled arrangement by means of side-by-side twin fittings. This arrangement increases the time required in connecting and disconnecting the hoses and complicates the operation.
Another problem involved in the unloading operation is the prevention of overflow. If the storage tank is filled before the valve is cut off at the truck, a considerable quantity of gasoline will remain in the hose which must be disposed of before the hose is disconnected to prevent spilling on the ground or pavement. No mechanical provision is provided in the prior art for this function. In the case of the very large hoses employed for rapid unloading, this is an important consideration.